


Celebration

by Storyflight



Series: BSD/DR Crossover Collection [3]
Category: Dangan Ronpa - All Media Types, 文豪ストレイドッグス | Bungou Stray Dogs
Genre: Aged-Up Character(s), All of the DR characters are around 20-22, BSD characters be like...idk...the same age but maybe one or two years older, Bad Writing, Birthday, Birthday Fluff, Birthday Party, Crossover, Crossovers & Fandom Fusions, Fluff, Gen, Happy, Happy Birthday Saihara Shuichi, Marriage Proposal, Minor Akamatsu Kaede/Harukawa Maki, Minor Edogawa Ranpo/Edgar Allan Poe (Bungou Stray Dogs), Party, Tooth-Rotting Fluff, VERY MINOR Kunikida x Yosano if u squint really hard, YES Louisa and Kirumi are in love and gay, it doesnt matter
Language: English
Status: Completed
Published: 2019-09-08
Updated: 2019-09-08
Packaged: 2020-10-12 03:43:12
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,104
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20557661
Author URL: https://archiveofourown.org/users/Storyflight/pseuds/Storyflight
Summary: He never liked surprises, he never liked loud noises, he never liked having all of these colours in his vision...but it’s the thought that counts, right? Even then, he was growing nervous and wanted Naomi to shut the door.It did not last long. Before it grew worse, he felt arms wrap around his waist and lips gently pressing against his own.“Happy Birthday, Shuichi” Rantaro’s voice was quiet and affectionate, with the eyes he could stare into all day.---Shuichi's loved ones throw a Birthday party for him.





	Celebration

**Author's Note:**

> Everyone: Did you really write a BSD/DR crossover for Shuichi's Birthday
> 
> Me: Absolutely
> 
> Happy birthday to one of my favourite characters in DR <333 He means a lot to me...I love him and he deserves all of the happiness.
> 
> I didn't mention EVERYONE but yes, the whole cast of v3 is there, having a good ol time, yea...

“You’re  _ late!” _

Ranpo? Upset about tardiness? Scolding someone like Kunikida? That's new.

He tapped his foot while looking at the distressed Rantaro. They looked down at the ground in shame.

“I know! I know!” They sighed, “I was trying my best to get here but I-I was rehearsing and m-making sure that everything was r-right!! Then there is the cake! And double-checking if I-I had everything—“

"It took an HOUR?! You better be lucky that he isn't here yet!"

"I said I was sorry!"

“I believe you two should end the quarrelling” Kirumi stood up from her seat, “What matters is that Rantaro is here and Shuichi is still out with Naomi. Everyone can now relax..."

"Thank you, Kirumi..." Rantaro was pleased that the maid faced this very calmly. She hated when others were late and often gave a large lecture about there actions. She let Rantaro slide this time, maybe it’s because Louisa is with her and did not want to scare her girlfriend.

“Tch...whatever”

“Edogawa seems more distressed about the party than anyone else…” Kaede whispered to Maki, “It isn’t even  _ his  _ party…”  
"I would be upset too if someone was late to an event..."

Members of the Agency, past members of Hope’s Peak, and a few miscellaneous (Guild and Port Mafia members, because their partner was here) were all here for Shuichi’s surprise birthday party. After a long night of decorating and preparing food, everything looked splendid and ready for the special boy. Rantaro was not a part of the "night mission", they were out with Shuichi for a birthday dinner. The one thing they had to worry about party-wise is to pick up the cake.  
Now morning, Naomi was with the detective this time and kept him busy. 

“Here’s the cake…” They wheezed, “Please don’t eat it right away…”

“I have manners! Besides, we have snacks!"

Ranpo took the cake and placed it on the table.

_ Everything will be okay…I'm here now... _

"Are you okay, Rantaro?" Kirumi asked them, "All of us were very worried about you..."  
"I am fine...thank you for asking"

“I got a text from Naomi!!” Tanizaki called, “They are on the train and returning to the Agency. So we have about...half an hour”

"Okay, not okay anymore" They started to tremble after that announcement. They wanted to have Shuichi’s birthday be special, but what if it messes up?! What if there is an ambush?! Anything could happen…

"I'm fucked"

“Maybe you should sit down..." Kirumi suggested, "And wait till he is here"

Waiting…

Like that’s any better. 

Rantaro took a seat next to Yosano and Mikan, still having the worst-case scenarios running through their mind. They would be calmer if they didn’t come by an hour late. How many people did they end up worrying?

"I'm so sorry, I let everyone down...again"

“R-Rantaro...It's okay"

"I made Ranpo angry! That never happens!"

"H-He cares for S-Shuichi as well and w-wants what is best for h-him…t-that's all” Mikan rubbed their back in comfort, “I'm sure he’s fine now that you’re here…”

“...Fine  _ now,  _ but I know he was very frustrated beforehand”

Mikan didn’t speak.

“Thought so”

“Stop that, it’s over,” Yosano said, “Water under the bridge...with Dazai in it too”

“Wait a minute…” Mikan had a look of confusion when that name was mentioned.

“W-Where is Dazai?”

All of the small chatter disappeared. Others looked at one another with looks of  _ “I thought you were watching him!” “Wasn’t he just here?!” “I have no idea”. _

"I believe Dazai went to go buy more drinks...?" Kenji said

Chuuya blinked. "Did he go alone?"

....

.....

......

“DAZAI!!!!” Kunikida bolted out of his seat, knocking down Kaito, and left the Agency.

“Ow! Hey! Uncalled for, Kunikida!!”

“He’s gone now, so it doesn’t matter” Margaret muttered

“B-But…” Louisa squeaked, “Rantaro looks worse”

Rantaro had their face buried in their hands.  
This is a recipe for disaster.

“H-Hey...Rantaro”

“I will handle this, Mikan,” Ranpo said, making them feel worse.

The detective kneeled to their level and stroked their shoulder. He had a calmer vibe, so he’s no longer upset like earlier...or he hopes. Rantaro looked up to find bright green eyes staring fondly at the nervous forest gaze.

"I-I uh..."

“Akiko helped me rehearse, want to do that?” He chuckled, “Trust me, this will make you feel much better”

“Yeah…Thank you"

“Alright, come with me!” He stood back up and stretched out his arms, “We will go in one of the vacant rooms! AKIKO-CHAN, hold the fort down”

“Understood” She stood up with Mikan following behind. “Kirumi and Louisa, you handle the video call! Hirotsu and Fukuzawa, see if any food needs to be replenished! Mikan, I need you to keep in contact with Doppo.”

Rantaro followed Ranpo to the room.

_ Everything will be okay.  _

——

What a rocky train ride, Shuichi was never a fan. On the bright side, they had Mochi ice cream as a small birthday treat.

"Sooooooooooooo..."

"....So?"

“How was your dinner with Rantaro last night?” Naomi asked with half a Mochi in her mouth.

“Where do I begin…?” He tapped the table thoughtfully, “One word, beautiful”

“The dinner or Rantaro?”

“I suppose both” he laughed, “It was dinner at a pier. Looking at the sea late at night was something I never thought I would enjoy…the food was amazing...expensive too…”

“Aren’t they rich?! It’s not that much of a problem. It’s like how it is with Ranpo and Poe, I know Ranpo doesn’t use it to his advantage…”

Shuichi nodded. “But I never like...using so much of their money, ya know? I don’t want to feel greedy. They do love spoiling me when they have a chance. I-I...I like it”

“Oh, I bet you were spoiled  _ a lot  _ once you made it home!”

“NAOMI!”

Naomi and Shuichi had to drop off some paperwork to a judge today, way too early in the morning and an hour away from Yokohama. Rantaro and Shuichi went to bed late and the loud knock was not a nice way to wake up on a Saturday. Naomi was at the other side with a bright smile on her face, stating that they had a job to do, and had ten minutes to get ready. Rantaro was a little upset he had to go, it meant less cuddling.

Shuichi was so tired, he wanted to go home. It was Saturday and doesn’t work on the weekends, but today he had to go back and talk about recent reports with Kunikida. As much as he wanted to postpone it, he did not want to disappoint him. 

The train stopped and the two made their way back to the Agency. To this day, he is in shock about the progress he made from being Ranpo's shadow when he was a Senior to a passing his entrance examine two years later. 

How time passes…

“Are you going to do anything else for your birthday? After all, it is today!”

“I’m not sure, whatever Rantaro has planned? They love birthdays after all...usually go all out if they can”

“Ranpo is the same way! So maybe those two will combine forces”

_ That sounds scary… _

“Oh! What about your past classmates?! Are they in Yokohama right now?”

"A couple are..." Kaede had a concert this month, which means she and Maki are settling in Yokohama temporarily. They texted ‘Happy Birthday’ and will quickly stop by tonight. Kirumi and Louisa planned on visiting the Agency to drop his gift later today.

The others? He was not so sure. Kaito said there was a gift coming his way and the others gave their happy greetings. He’s not expecting much, which is fine. No one needs to take time out of their day for Shuichi’s birthday.

_ It’s a shame I’m unable to see Ryusei…  _ His Uncle had an emergency trip to the Philippines and wouldn’t return till next week.

Once they made it to the room, Naomi opened the door for him.

"What was that for? I usua-"

Loud cheers and bright colours interrupted him.

"E-EH?!"

“S-SURPRISE!!”

“HAPPY BIRTHDAY!”

“HAPPY SHUICHI DAY!”

“WE LOVE YOU, SHUICHI!”

“BORN DAY! BORN DAY!”

“IT'S ALL ABOUT MY SIDEKICK TODAY!”

Several poppers went off with string falling on his shoulders and hair. Who did this? Ranpo? Rantaro? Fukuzawa? Everyone?

Everyone...?

Everyone was here.

Shuichi was growing overwhelmed.

He never liked surprises, he never liked loud noises, he never liked having all of these colours in his vision...but it’s the thought that counts, right? Even then, he was growing nervous and wanted Naomi to shut the door.

It did not last long. Before it grew worse, he felt arms wrap around his waist and lips gently pressing against his own.

“Happy Birthday, Shuichi” Rantaro’s voice was quiet and affectionate, with the eyes he could stare into all day.

“Happy birthday!” Ranpo and Poe followed behind and kept their distance, “Surprise! Kunikida doesn’t need you to look at reports! That’s his gift to you”

“Honestly, I’m okay with that gift” He was talking to Ranpo, but he was still staring at Rantaro. He pulled them in for another kiss.

“Aaaawww, I could cry” Kaito sniffed

“EEEWWWW!” Kokichi and Yumeno said at the same time.

“Look at those dorks” Kaede giggled

“Hey! Save that for the bedroom!”

“NAOMI!” Shuichi broke the kiss, “Not this again!”

“She has a point” They nuzzled noses with him childishly, “We can continue kissing a little later…”

“Unfair” 

“Totally fair! Come on!!” Naomi pushed the couple further into the building, “It’s time to enjoy yourself! And look!! Your friends are here!!”

“Shuichi, my man!!” Kaito beamed, “I haven’t seen you in forever!! It’s great to see you on your special day!!”

“You have grown” Hajime complimented, “May I say that your voice is much deeper than before”

“I’m so proud of you” Kyoko had a small smile, but there was so much emotion in it.

“And we have someone special with us” Kirumi held out a small laptop. Why in the world does she have a laptop?

Wait…

“Is that a video call?”

_ “Hey, Shuichi!” _

“RYUSEI! You’re here!” He wasn’t here-here, but this was enough for him. 

“NOW! LET THE FESTIVITIES BEGAN!” Rantaro held raised their hand proudly, still holding Shuichi’s and lifting him slightly.

“H-Hey!”

“Sorry!!”

——

“May I have everyone’s attention?” Fukuzawa started to lightly tap on the glass.

About an hour in and everything was going well. All of the food was amazing and the guests were enjoying themselves. Some of Shuichi’s classmates never met the agency and company, they get along quite well.

Kenji and Kaede were already the best of friends. He promised to go to one of her concerts with Yumeno as his plus one. How can everyone see when there are two personifications of sunshine in the same room and interacting?

Chuuya met Angie. The artist mentioned that her image of Atua looked just like him. He sort of shrugged it off and listened to whatever she talked about. Chuuya was invested nonetheless.

Kyoko and Poe had a nice conversation about murder mysteries. It looks like at the end of this party, they will give her a book to read.

Then there are the others who already knew one another. Mikan was mentored by Yosano back in Hope’s Peak and stayed by her side. Louisa had to keep Kirumi grounded, requesting her to not serve for this party. She accepted and mingled with everyone else. Louisa met up with Mikan and Kirumi talked to Yosano.

“...I say that we should all share some words about the birthday boy”

“What?” He squeaked. Shuichi had a drink in his hand and other holding Rantaro’s hand. He also wore a silly top hat saying “It’s a Boy!”, thanks to Kaito and Atsushi. 

“You do not have to speak if you wish not to, but—“

“I call going first!” Ranpo was sitting on top of a table with Poe next to him.

"The floor is yours"

“Hey, Kid. When Hope’s Peak asked me to come by to talk about my job, I was not interested at all! Me? Talking to some kids about being a detective? I dragged Akiko with me so I was not alone, but we talked to different classes. I had yours and then I met you. Oooooh boy, I saw so much potential in you, I knew that there was something special! That’s when I decided to take you in as my apprentice. You will always be my apprentice, even if you are a member, and I’m proud to watch you grow up…”

Shuichi felt like he was going to cry.

“...Ranpo…”

“Ranpo tells me all of your progress” Poe confessed and wrapped one arm around their husband, “And I’m proud of you as well...Shuichi, you’re like the son we never had”

The son they never had…

Hearing that and having not the best relationship with his parents moved him...

“I knew that you would succeed and reach far, further than myself” It was Kyoko who spoke, “I do wish that you were confident with yourself, many situations would be easier for you”

“Hey!” Kaito raised his hand, “You taught me so many things! Training with you made me grow as a person in and out! And look at you, reaching for the stars!”

“A-Ah…” all of these compliments, all of this praise, does he deserve all of this?

“I’ll be right back” Rantaro whispered and hurried over to Ranpo.

Why were they leaving? It was not to the bathroom or to get more food. Is everything okay with them?

There was inaudible talking, then Ranpo nodded and playfully ruffled their hair.

_ What’s going on… _

“Lad” Fukuzawa sighed, “I don’t know what to expect when Ranpo said that he taking you on as an apprentice. You and Mikan surprised me with your skills and adapting to the agency’s workplace, I’m proud that both of you are in our family...It’s safe to say you’re the grandson I never had”

“...Fukuzawa” he breathed.

_ Don’t cry. Don’t cry. Don’t cry. _

_ “He’s right”  _ Ryusei’s voice was heard from the laptop, _ “Here you are a part of a gifted organisation! You surpassed my skills as a detective” _

“BEST FRIEND!” Kaede squealed, “Happy birthday!! I love you so much, I would die for you, no doubts about it!"  
"Please do not, Kaede..."  
"Fine, I would commit tax fraud for you! ANYWAY! I’m so happy to meet someone like yourself. You helped me through so much...you have grown so much...and I just…” the pianist was starting to grow emotional. Maki rubbed her back and tried to calm her down.

“What she was trying to say is...we care about you” Maki finished.

“It’s a pleasure to work with you, Shu-Shu!” Naomi laughed

“And you’re a valued member of the agency…”

“And a graduated Hope’s Peak student from Class 79!! To Shuichi Saihara!” Angie raised a glass for a toast.

“TO SHUICHI SAIHARA!”

  
  


_ All of this for me….  _

Shuichi smiled shyly. 

_ They’re doing all of this for me. _

Shuichi wanted to repay everyone right now. He wanted to throw them a party for all of their hard work and love. This was his family, by blood or work or school, these were all of the people that cared for Shuichi.

“Th—“

“Shuichi?” 

There was one more person who didn’t say anything.

Well, many did not say anything and that’s fine. Shuichi was not expecting each person to give a speech, especially the guest who are not as familiar with the detective. Hajime had a long talk with him yesterday, so he was quiet today. Tanizaki’s words were the same as Naomi’s, and Atsushi was not much of a talker.

Rantaro didn’t say anything, but now they spoke up. 

The Adventurer had an adorable smile on their face, followed by a shy wave. They stood in front of him with one hand behind their back and anxiously bouncing on their toes.

“...Rantaro?”

“I...Shuichi” they averted their gaze for a moment, “Words cannot describe how much I love you. I’m so happy that I was even able to be friends with you. I know I have my moments, I know I make risky decisions, I know that I can be a complete idiot sometimes…”

“Only sometimes?”

“Hey!” Rantaro walked closer to him and poked Shuichi’s forehead, “Okay, more often than usual. But even through all of that...even when I’m at my worst, you still stick with me. That’s when I slowly…very slowly realised that I was falling for you. Shuichi, I love you so much”

“...I love you too”

“No, I...I really love you. Shuichi, I-It’s…”

“Are you okay?”

He was growing worried, why was Rantaro growing nervous? Shuichi was waiting for them to say that they had to leave for a long time, caught a terrible illness, wanted to break up with him, anything bad.

But no,

It was none of that.

Instead, Rantaro got down on one knee.

“R-Ra—“

“Oh my god”

“You owe me, Kokichi”

“They’re doing it!”

“That’s my child…”

Was this happening?!

“Shuichi Saihara, will...will y-you take this special adventure with me and...a-and m-marry me?”

That’s when he saw the irresistible ring and Rantaro’s loving look. 

“R-Rantaro! I—I”

_Is this all a dream?_

Today was too much. First, he found out he had to leave early, then had to go to work, then found out it was just a party, have everyone he loves here, gifts, loving words, and now…

Rantaro was proposing to him.

His eyes grew wet with tears falling down on his face. Great, he is ruining the whole moment and crying in front of everyone.

“A-Ah! I didn’t mean to cry!!” He choked and wiped his wet face. “YES! YES, I will marry you!!”

“You will?! A-Are you sure?!"

“Yes! YES! YES! YES!” Shuichi found himself jumping up and down. Rantaro was not far behind and pulled him into a very tight hug.

Now the engaged couple were spinning, jumping, and crying together.

"A-AHAHA!"  
"AH!"

“WOOO!!!”

“GIVE IT UP FOR SHUICHI AND RANTARO”

“ABOUT TIME!!”

“I AM SO HAPPY FOR YOU BOTH!!”

“Rantaro! Rantaro I—“ he was growing a little dizzy from the moment, “I love you!”

“I love you too!!” They laughed, “I’m...Aaaah! We are getting married!!”

Everyone else started to clap or join in on the hug. Ranpo and Kaede took no time sharing the love, others slowly started to pile in.

He’s drowning in love and people right now, quite bittersweet.

But this was the best birthday he has ever had. 


End file.
